Investigation of the food value chain of ready-to-eat chicken and the associated risk for staphylococcal food poisoning in Tshwane Metropole, South Africa

The objective of the study was to better understand the informal markets for ready-to-eat (RTE) chicken in Tshwane Metropole, Gauteng Province, South Africa, and in particular the links between the formal and informal sector. As part of this, we assessed the risk of a common food poisoning (staphylococcal) through consumption of RTE chicken sold by informal vendors. We used participatory risk assessment, a novel approach to understanding food safety in data scarce environments to collect information. Structured interviews and focus group discussions with informal vendors (n = 237) were conducted to understand poultry value chains for informal RTE chicken, business operation and hygiene practices. Samples (n = 100) of RTE were collected from informal vendors in six major taxi ranks. Staphylococcus aureus counts were determined using 3M^ Petrifilm^ plates. Data collected in this present study plus information obtained from reviewing of literature, were used to develop a stochastic risk model. The number of colonies which were too numerous to count (TNTC) was artificially modeled. A mapping of the informal food value chain revealed that there are four possible value chains and that chicken spilled over from formal to informal markets. The prevalence of S. aureus in RTE chicken samples (44%; 90% CI: 36.1%-52.2%) was high. The mean S. aureus counts in the ready to eat chicken was 10^ (90%CI: 10^3-10^), and the risk of purchasing chicken of unsatisfactory quality (>10^3 cfu/g) was 32.9% (90%CI: 25.5%-40.4%). The probability of food poisoning due to consumption of RTE chicken contaminated with staphylococcal enterotoxin was estimated to be 1.3% (90% CI: 0%-2.7%). Sensitivity analysis showed that the probability of S. aureus having the enterotoxin gene was the most sensitive parameter for food poisoning. This was followed by S. aureus concentration in RTE chicken and lastly the prevalence of S. aureus in ready-to-eat chicken. This study demonstrates the existence of a strong link between formal and the informal market. In view of the low risk observed, the relevant authorities in Tshwane should continue to support the informal sale of RTE chicken. However, there is still a need for provision of hygiene training to reduce the concentration levels of S. aureus on the RTE chicken, and to promote the sale of safer affordable source of protein for the large urban poor population in South Africa. This will also help secure the opportunities for employment associated with the trade